Electrical control system



April 26, 1960 F. D. LOW 2,934,074

ELECTRICAL CONTROL SYSTEM Filed Feb. 19, 1958 2 Sheets-Sheet 1 nov. so AC I Y 02 a 59 cs 30 c J J 51 7 26 mmvrox.

32 FRANK 0. LOW BY 25 M 4/ R0 ND G U ATTORNEY April 26, 1960 F. D. LOW

ELECTRICAL comer. SYSTEM 2 Sheets-Sheet 2 Filed Feb. 19, 1958 INVENTOR.

FRANK D. LOW

ATTORNEY 2,934,074 ELECTRICAL CONTROL SYSTEM Frank D. Low, La Grange Park, Ill., assignor to General Electric Company, a corporation of New York Application February 19, 1958, Serial No. 716,059

8 Claims. ,(Cl. 134-58) .Thisinvention relates to electrical controlsystems, and, inparticular, to a control system for automatically effectiug a change in an electric circuit as a latch or the like is manipulated to disengage the strikeand'keeper elements of the latch.

There are numerous situations in which electrical apparatus within a chamber or the like must be de-energized before opening the door of the chamber. It-is common practice, in such situations, to use a normally open switch having an actuator which the dooritself urges into circuit closing position as .the door closes; and, of course, the switch returns to open circuit position as the door releases the actuator. A disadvantage of such arrangement is that the door is at leastipartly open before theswitch assumes an open circuit positionl Because it is natural to opena door inacontinuous'motion; the electrical Japparatus within the chamberrnay have had insufficient opportunity to come .to a stop before the door reaches a rather widely open position. A typical example ofapparatus inwhich conventional door-operated circuit contro'ls have proven extremely disadvantageous is an electric dishwasher in which the articles in'the washing chamber are being subjected to jets and sprays of washingliquid which are forcefully circulated by means .of electrically actuated pumps. The'user' of the dishwasher, particularly if it is of the domestic type, may wish to open the cabinet to add an article during a washing operation. Therefore if the operator is careless in opening the cabinet door, even a brief continued operation of the liquid circulation means will make it almost inevitable that liquid will escape fromthe washing chamber into the kitchen. It has been proposed to have door latches which'are electrically controlled and operable to open position only when the electric power circuit is interrupted; but the expense and relative complexity of such mechanisms 'have made them commercially unacceptable. Pursuant to the present invention, a door latch of a dishwasher or the like embodies a switch having an actuator whichis 'engaged'bya component of thelatch and operated thereby to closed circuit position' as the door is closed. The switch is so arranged, however, that during the act of disengagement of thekeeper from the strike, but prior to the actual separation of the keeperfrom the strike, the switch willassume a normally open position. Thus, the electric circuit is broken before the latchreleases the door, and even though the interval prior to the'actual opening of the door is brief, the water circulationm eans is at substantially full stop before the door may be opened su'fliciently to allow escape of liquid.

It'is therefore an object of the invention to providean electrical control systemwhich is associate'd'with a door latch insuch fashion that it assumes a desired electric circuit condition as an incident to the operation of disengagement of the keeper from the strike of the latch but prior to the actual disengagement of these elements.

lt is'another objectof the invention to provide an elec- Itricgcircuit. control. system which is directly operable by a;latchingxmechanism .used on, adoor of a chamber con ice taining electrically driven equipment, pursuant to which operation of the door latch'eliects a change in the operative status of such equipment.

It is a further object of the invention to provide a combination door latch and electric switch.

Other features and advantages of the invention will be obvious from the description of a presently preferred embodiment thereof, read in connectionwith the accent panying drawings in which:

Fig. l is a side sectional elevation of a dishwasher embodying a control system according to the presentinvention, portions of the dishwasher housing'and-tub being -rokenaway to reveal underlying structure;

Fig. 2 is a fragmentary front elevation of "the {dishwasher door taken on the line 2-2 of- Fig. 1, showing the relationship thereto of the latch mechanism and control switch;

Figs. 3 and 3a are side sectional elevations'taken on lines 3-3 of Fig. 2 and respectively showing the latch and switch mechanism when in the latchedand the unlatched positions;

Fig. 4 is a rear perspective view of the latch keeper assembly;

Fig. 5 is a sectional elevation of a typical switch taken on lines 55 of Fig. 3; and

Fig. 6 is a schematic diagram of the electrical control circuit of the dishwashing machine. My invention is illustrated in its application to aco'nventional automatic dishwasher of the domestictype. shown in Fig. 1, such a dishwasher comprises a housingfl containing a tub 2 having an upper rack 3 and a, lower rack 4. The racks are provided with rollers cooperating with trackways (such as the rollers 5 and trackway6 at the upper rack) pursuantto which the racks may be drawn forwardly of the tub when the tub door 7 is swung to its open position. It will be understood thatthedoor 7 is a substantially hollow structure, provided withsuitable hinges (not shown).adjacent its bottom edge, whereby the door may be manually operated betweena verti cal closed position and asubstantially horizontal open position. When the door is in itslatter position, the racks may be withdrawn through the door opening to permit them to be loaded and unloaded. As best shownin'Fig. 3, there is a soft rubber-like gasket 8 disposed about'the periphery of the door. Said gasket compresses against a peripheral rim 9 of the tub 2 to seal the dooragainst leakage of liquid during operation of the dishwasher. The apparatus for introducing water into the-tub and for circulating the water throughout the tub during thewashing and rinsing operations comprises a water. inlet -valve 10 connected by a pipell to a suitable source (not shown) of heated water and having a discharge tube 12 which supplies water to the tubby way of an inl'etifittiiig 14 mounted on an exterior side wall of the tub. Thevalye It) is of the normally closed typeand is operatedto open position by a solenoid coil 15. Further,. the liquid circulation apparatus includes a pump 16 driven by an electric motor (17, Fig. 6). The pump receives liquid from the tub through the inlet fitting-18 and discharges theliq'uid under substantial pressure through the standpipe llwhicjh supplies the lower reaction spraydevice 20. Thedevice 28 is arranged to be coupled toa tube21 rotatably supported by the lower rack 4 and terminating in a second rotatable spray device22. The respective devices 20 and drain fitting 24, a drain pump 25 drivenby an electric m e 26 i -1 )v a ad sha se hose wh m:

municates with the plumbing drain system (not shown] of the building.

In the use of a dishwasher of this type, the user loads the racks and returns them to the tub 2, places a quantity of a suitable detergent in a receptacle (not shown) on the door, closes the door, and initiates the operation of the apparatus by turning the knob of the time-cycle controller 30. The controller includes cams C1 to C5, inclusive, which respectively control the timer motor 31, the water valve solenoid 25, the main pump motor 17, the heating element 32, and the drain pump motor 26. As is well known, the various cams operate to close and open the electric circuits of the associated components in a-predetermined cycle designed to wash, rinse, and dry the articles in the tub.

It will be noted that the control circuit includes a switch 33 which, when open, will interrupt the current supply to the electrical components. This switch is arranged in operative relation to the door latch pursuant to the present invention.

As best shown in Fig. 3, the upper front portion of the door 7 is arranged to provide a hand-grip by inwardly embossing a portion 34 of the door panel and folding back a rim 35. This embossing and folding process provides a relatively long opening 36; this opening provides for the passage of the fingers as the door is grasped to open it. The users fingers will come into contact with the door latch actuator at this time, whereupon suitable finger pressure will actuate the latch to disengage the respective keeper and strike elements of the latch.

The latch mechanism includes a strike 37 mounted on an exterior top wall portion 38 of the tub 2. Said strike has a nose characterized by a sloping forward wall 39 and a vertical rear wall 40. The strike is arranged for adjustment relative to its projection forwardly of the tub wall; the machine screw 41 passing through the elongated opening 42 in the strike is a simple way of adjustably securing the strike. It will be observed that when the door 7 is closed, the tub wall 38 and strike 37 are in vertically spaced overlapping relation with the top forward wall 43 of the door.

The latch mechanism further includes a keeper 44 pivotally mounted within the door. The mounting means for said keeper comprises a bracket 45, see Fig. 4, having upwardly offset ears 46 by means of which the bracket 45 is secured to the underside of the wall 43 of the door. The bracket further includes a portion 47 which forms a substantially cylindrical housing for the accommodation of a pin 48 and a torsion spring 49. The keeper 44 has a tongue portion 50 and an actuator 51. The keeper is pivotally mounted on the pin 48 and is urged by the spring 49 into counterclockwise rotation, as viewed in Fig. 3. The tongue has a downwardly sloping pilot portion 52 and an aperture 53 through which the nose of the strike projects as the door reaches home position. It will be obvious from Fig. 3 that because of the abruptly vertical rear wall 40 of the strike and the engagement of said wall with the adjacent edge wall of the aperture 53, it is impossible to open the door without first rotating the keeper in a clockwise direction to the extent necessary completely to disengage the tongue from the strike.

. Preferably, the strike 37 is adjusted relative to the tub to require the compression of the gasket 8 before the wall 40 may enter the aperture 53. By this means, the seal of the door against the tub is maintained for a brief interval after the actual disengagement of the latch.

The control switch 33 is so arranged that it will be actuated to closed circuit position by engagement with the nose of the strike as the door is closed and restored to open circuit position before the actual disengagement of the keeper from the strike. This can conveniently be done by mounting the switch for displacement relative to the strike. It is advantageous to have this displac ment occur as the keeper itself is rotated, and the switch is therefore mounted on the keeper. As shown in Figs. 3 and 4, the actuator portion 51 of the keeper has downwardly turned side walls 54. A switch mounting bracket 55 has side walls 56 which are secured to the walls 54 by rivets 57. The side walls 56 are also traversed by the pin 48, whereupon the switch mounting bracket is accurately positioned relative to the keeper assembly. The switch 33 is adjustably mounted on the wall 58 of the bracket 55 by suitable machine screws, such as shown at 60, Fig. 3, which respectively pass through an opening 61 and a slot 62 in the bracket 55.

Switch 33 is of the single pole, single throw type in which a contact 63 is spring biased to maintain a normally open condition relative to contact 64. The illus trated lead wires are connected into the electrical circuit, as indicated in Fig. 6. Most of the control circuit wiring is within the door 7, pursuant to conventional practice. Contact 63 bears directly against the plunger-type switch actuator 65 to urge it in an upward direction, as viewed in Fig. 5. The switch is mounted on the bracket 55 so that the actuator guide 66 will pass freely through the opening 67 in bracket 45 and the actuator 65 will abut against the under surface of the tongue 50 of the keeper, when the keeper is withdrawn from the strike, but will nevertheless have sufficient exposure relative to the aperture 53 to be engaged by the strike and moved thereby to closethe contacts 63 and 64 as the keeper reaches its door-securing position. The relationship of the actuator to the tongue of the keeper protects the actuator against forces which might otherwise be exerted laterally thereon by the strike; for if the actuator normally projected upwardly through the aperture 53 in the tongue, it would engage the nose of the strike as the door approaches its closed position. Even though the front portion 39 of the strike is sloped and thereby would sweep across the actuator, a slamming action of the door could result in damage to the switch actuator by the strike.

Switch 33 is adjusted relative to the keeper and the strike so that the switch contacts will open before the keeper disengages from the strike and will close only after the keeper and strike have come into partial engagement. This insures that the control circuit will be open before the door is even slightly ajar, for the door cannot be opened until the latch elements have disengaged. It will also be apparent that the electric circuit cannot be closed until the door is fully closed. Switch adjustment may be effected by insertion of a screwdriver through the opening 36 to loosen the mounting screw which passes through the slot 62 in the mounting bracket, whereupon the switch may be moved up or down on the bracket as necessary.

In contrast to the door'operated switch devices of the prior art, in which the switch attained open-circuit condition as a result of the opening of the door, the present invention provides a brief interval between the interruption of the'electric circuit and the actual opening of the door. Although this interval is a matter only of one or two seconds, it is nevertheless sufiicient to reduce water action to a degree making it impossible for the water to splash through the door opening. The back pressure of the pump 16 places a considerable load on the motor, and the pump resistance brings the motor to a very quick stop. The resulting drop in liquid pressure reduces the discharge from the reaction spray devices 20 and 22 to feeble streams which will not reach through the spaces about the partially opened door. a

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various modifications may be made therein, and it is intended to cover in the appended claims' all such modifications as fall within the scope of the invention.

1 claim:

1. In an appliance having a cabinet, a hollow door for said cabinet, said door having an aperture affording access to the interior thereof, electrically actuated means said cabinet, and *1 anelectric power circuit 9' for said electrically actuated means; a combination door latch and ,circuit .-,control means comprising a strike mounted onsaid cabinet, a latch mechanism having a keeper comprisingan actuator portion and a tongue portion; said tongue portion; having wall means for engagementtwit-hfsaid strike, to establish the door in closed position, bracket means fixed within said door for pivotallyamoUnting said keeper for rotation relative to said strike,.the actuatorportion of said keeper being accessiblegthrough said door opening for manual rotation of said: keeper in a direction separating said tongue portion from said strike, a switch inseries electrical relation in said circuit, means for biasing said switch to ,a first electrical circuit condition, an actuator on said switch to operate the same .to a-second electrical circuit condition, bracket ,means for mounting said switch on said keeper .for; movement therewith,and ,means'for positioning said switch 'on'said'bracketmeans 'for the engagement of said switch actuator by said strike and movement thereby to establish said second circuit condition as said latch attains its door-holding position and the release of said switch actuator for return of the switch to said first circuit condition during movement of said keeper in a direction separating said keeper from said strike.

2. In an appliance having a cabinet, a hollow door for said cabinet, said door having an aperture affording access to the interior thereof, electrically actuated means within said cabinet, and an electric power circuit for said electrically actuated means; a combination door latch and circuit control means comprising a strike mounted on said cabinet, a latch vmechanism having a keeper comprising an actuator portion and a tongue portion, said tongue portion having wall means for engagement with said strike to establish the door in closed position, bracket means fixed within said door 'for pivotally mounting said keeper for rotation relative to said strike, the actuator portion of said keeper being accessible thorugh said door opening for manual rotation of said keeper in a direction separating said tongue portion from said strike, a switch in series electrical relation in said circuit, means for biasing said switch to a first electrical circuit condition, an actuator on said switch to operate the same to a second electrical circuit condition, bracket means for mounting said switch on said keeper for movement therewith, and means to operate said switch actuator to establish said second circuit condition as said latch attains its door-holding position and to release said switch for return thereof to said first circuit condition during movement or" said keeper in a direction separating said keeper from said strike.

3. In an appliance having a cabinet, a door for said cabinet affording access to the interior thereof, electri-v cally actuated means for introducing liquid into said cabinet and circulating it therein in the form of sprays and streams under substantial pressure, and an electric power circuit for said electrically actuated means; a combination door latch and circuit control means comprising a strike mounted on said cabinet, a latch member pivotally mounted on said door, said latch member having a keeper for engagement with said strike, spring means biasing said latch member into rotation in a direction maintaining the engagement of said keeper and said strike, whereby said keeper may be released from said strike only byrotation of said latch member in a disengaging direction, a switchlin series electrical relation in said circuit, means for biasing said switch to .a first electrical circuit condition, an actuator on said switch to urge the switch to a second electrical circuit condition, means for mounting said switch on said latch member for movement therewith, and means for adjusting the position of said switch relative to said keeper for operation of the switch actuator by the strike to establish said second electrical circuit condition as the door attains a closed position, said strike actuator releasing mounted on said cabinet for releasable engagement with.

said first latch mechanism, means for mounting said first latch mechanism for rotation in a latching or an unlatching direction relative to said second latch mechanism, a normally open electric switch insaid electric power circuit, an actuator forsaidswitch, means .for mounting said switch on said .firstlatch rnechanism. for movement therewith relative to saidsecond latchmechanism, spring meansforbiasing' said switchmounting means to effect engagement of said switch actuator by said second latch mechanism and operation thereby to effect a closed-circuit switch condition as the door attains its closed position, and means for adjusting said switch relative to said second latch mechanism for disengagement of said switch actuator from said second latch mechanism for return of the switch to open-circuit condition upon rotation of said first latch mechanism in an unlatching direction but before effecting the complete release thereof from said second latch mechanism.

5. In apparatus having a cabinet, a door for said cabinet, and electrically operated devices within said cabinet; the combination comprising a latch mechanism including a keeper, bracket means secured within said door, means for pivotally mounting said keeper on said bracket means, said keeper having an actuator portion and a tongue portion, said tongue portion having an aperture, a strike mounted on said cabinet, said strike having means defining a nose portion for projection through said aperture when said door attains a closed position, a rigid bracket on said keeper actuator, an electric circuit for energizing-said electrically operated devices, a switch for controlling. the energy flow in said circuit, an actuator for said switch, means for adjustablymounting said switch on said rigid bracket with said actuator below said keeper aperture, whereby when said door is closed the penetration of the nose of said strike through said aperture will engage the switch actuator to operate said switch to a first circuit condition, and means for biasing said switch to a second circuit condition upon rotation of said actuator in a predetermined direction, said keeper actuator being accessible through an opening in said door for manual rotation of said keeper in an unlatching direction.

6. In apparatus having a cabinet, a door for said cabinet, and electrically operated devices within said cabinet; the combination comprising a latch mechanism including a keeper pivotally mounted on said door, said keeper having an actuator portion and a tongue portion, said tongue portion having wall means defining an aperture,

a strike mounted on said cabinet, said strike having means defining a nose portion for projection through said aperture to releasably maintain said door in a closed position, an electric circuit for energizing said electrically operated devices, a switch for controlling the energy flow in said circuit, an actuator for said switch, means for mounting said switch on said keeper actuator portion with said actuator below said keeper aperture, whereby when said door is closed the penetration of the nose of said strike through said aperture will engage the switch actuator to operate said switch to a first circuit condition, means for biasing said switch to a second circuit condition upon rotation of said keeper in a direction to effect disengagement of said strike from said keeper tongue portion, and means for eflecting such rotation.

7. In apparatus having a cabinet, a door for said cabinet, and electrically operated devices within said cabinet; the combination comprising alatch strike on said cabinet, a latch for said door, said latch including a keeper mounted on said door for rotation into or out of engagement with said strike, whereby releasably to maintain the door in closed position, an electric circuit for energizing said electrically operated devices, a normally open switch in series in said circuit, an actuator for operating said switch to closed circuit condition, means for mounting said switch in fixed relation to said keeper for engagement of said'actuator by said strike and operation thereby to closed circuit condition as said keeper comes into latching relationship with said strike, means for biasing said switch for operation to open circuit position upon conjoint rotation of said keeper and said switch in a disengaging direction relative to said strike, and means for effecting said rotation.

8. In an apparatus having a cabinet, a door for said cabinet, and electrically operated devices within said cabinet; the combination comprising latch means for securing said door in closed position, means for manually moving said latch means to a position releasing said door, an electric circuit for energizing said electrically operated devices, a switch for controlling said circuit, means for mounting said switch-on said latch means for movement therewith, means actuated by said latch means for operating said switch to one electric circuit condition upon the door attaining a closed position, and means responsive to movement of said latch means toward its releasing position to actuate said switch to another electric circuit condition.

References Cited in the file of this patent UNITED STATES PATENTS 

